Apparatus and process for slag deposit removal

ABSTRACT

An apparatus for removing slag from the heat absorption surface in the furnace section and convection section of a heat exchanger including at least one blast nozzle disposed proximate to the surface and having at least two outlet orifices. A first fluid, such as water, is delivered to one of the orifices, and a second fluid, such as steam, is delivered to the other orifice to create a thermal shock and mechanical force which causes the slag deposits to separate from the heat absorption surface.

United States Patent 115 3,661,124 Winkin 1 51 May 9, 1972 541 APPARATUSAND PROCESS FOR SLAG 1.840.544 1/1932 Thomas ..122/392 DEPOSIT REMOVAL1,926.248 9/1933 Snow I 122/392 2,137,253 11/1938 Thompson. .....122/3921 lnvemofl Justin E Wmkm, Falrlawm 3.541999 11/1970 Winkin 122/392 F tWh l C t' L t [731 Assxgnee er ee er orpora wmgs on PrimaryE.\'ami/1erM. Henson Wood, .lr.

I Assistant Examiner-R. W. Thieme [22] Filed: June 19, 1970Attorney-John Maier, lll, Marvin A. Naigur and John E. W11- 21 Appl.No.1 47,694

[57] ABSTRACT 23 2 3 9/ An apparatus for removmg slag from the heatabsorptlon suri i face in the furnace section and convection section ofa heat 7 v "n 1') o [58] Field Search l/39 exchanger including at leastone blast nozzle disposed proximate to the surface and having at leasttwo outlet orifices. A [56] Rekrences cued first fluid, such as water,is delivered to one of the orifices, and UNITED STATES PATENTS a secondfluid, such as steam, is delivered to the other orifice to create athermal shock and mechanical force WhlCh causes goodmg the slag depositsto separate from the heat absorption surface. 1.18-1.98 ystrom...966.987 8/1910 Barnhill 122/392 4 Claims, 3 Drawing Figures PATENTEDMY 9m2 3,661 124 36 n l 28:13 m II z INVENTOR JUSTIN P WINKIN ATTORNEYSAPPARATUS AND PROCESS FOR SLAG DEPOSIT v REMOVAL BACKGROUND OF THEINVENTION This invention relates to an apparatus for removing slagdeposits from a heat exchanger, and, more particularly, to an apparatusfor removing slag deposits from the heat absorption surface of thefurnace and convection sections of a vapor generator.

In the generation of power from fossil fuels utilizing vapor generators,there is a major problem attendant in the firing of fuels having a highalkali metal content, due to the severe slag deposits that are formed onthe heat absorption surface in the furnace and convection section duringthe operation of the vapor generator. In the past, these deposits havebeen avoided primarily by restricting and blending the fuel and usingadditives. However, even with this restricted use of the fuel, theproblem of fouling heat transfer surfaces has still persisted to a greatdegree, rendering it necessary to use a large number of soot blowers,which add to the cost of the vapor generator.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide an apparatus for the removal of slag deposits fromthe heat absorption surface in the furnace and convection sections of avapor generator which does not restrict the use of the fuel and whicheliminates the use of additives, while minimizing the number of blowersrequired.

Toward the fulfillment of this object the present invention features theuse of a blast nozzle comprising a hollow body member, at least twooutlet orifices extending through a wall of said body member, firstdelivery means for delivering a first fluid to one of said orifices, andsecond delivery means for delivering a second fluid to the other of saidorifices.

BRIEF DESCRIPTION OF THE DRAWINGS The above brief description, as wellas further objects, features, and advantages of the present inventionwill be more fully appreciated by reference to the following detaileddescription of presently preferred but nonetheless illustrativeembodiments in accordance with the present invention when taken inconnection with the accompanying drawings wherein:

FIG. 1 is a partial section-partial schematic view looking at the sideand down on the furnace section of a vapor generator;

FIG. 2 is an enlarged sectional view taken along the line 2- 2 ofFlG. l;and

FIG. 3 is a sectional view taken along the line 33 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring specifically to FIG.1 of the drawings, a portion of the furnace section of a vapor generatoris shown schematically by the reference numeral 10. The furnace isformed by four walls, two of which are shown by the reference numeralsl2 and 14, it being understood that corresponding walls opposite andparallel to the walls 12 and 14 are also provided to form an enclosedstructure.

The walls 12 and 14 are of a fin-tube construction as shownschematically, and are surrounded by insulating walls 16 and 18respectively. The inner surfaces of the walls 12 and 14 form the heatabsorption surface of the furnace section in a relatively heavy slagzone extending from the bottom portion of the furnace section up to thetop height thereof. A plurality of rows of fin-tubes, shown in generalby the reference numeral 20, form the superheater portion of the furnacesection 10.

According to the present invention, each wall forming the furnacesection 10, along with its corresponding'insulating wall, is providedwith a plurality of openings extending therethrough for accomodating acorresponding number of blast nozzles. For the purpose of example, onlyone hole 12a and its corresponding hole 16a, is shown extending throughthe fin-tube wall 12 and the insulating wall 16, it being understoodthat several more may be provided in this wall and the other walls forde-slagging the furnace walls, superheater walls in the furnace andother heat absorbing surfaces in the convection section.

The blast nozzle is shown by the reference numeral 22, and is adapted tobe moved between a retracted position shown by the solid lines in FIG.I, and an extended, operative position shown by the broken lines. Thismovement is achieved by means of a drive unit 24 which is connected tothe nozzle 22 by means of a lance tube 26. The drive unit is morecompletely described in US. Pat. Application Ser. No. 759,184, filedSept. I1, 1968 and assigned to the assignee of the present invention, itbeing sufficient for the purposes of the present application to notethat it is adapted to move along a pair of tracks 28 to and from theretracted and extended position of the nozzle 22, and that it includesmeans to impart a rotational drive to the nozzle.

A control system 30 is operatively connected to the drive unit 24 inorder to control the above-mentioned movements of the nozzle 22, and todistribute steam and water from sources 32 and 34, respectively, to thenozzle via the drive unit 24 and the lance tube 26. The connectionsbetween these components are shown schematically by the referencenumeral 36.

The details of the nozzle 22 are shown in FIGS. 2 and 3. Specifically,the nozzle comprises a hollow body member 40 having a pair of axiallyspaced, radially extending orifices 42 and 44 extending therethrough forrespectively distributing steam and water through the nozzle. Inparticular, the lance tube 26 is directly connected to the body member40 for supplying steam from the source 32 to the orifice 42 via thecontrol system 30 and the drive unit 24. A water tube 46 is coaxiallydisposed within the lance tube 26 and connects the water source 34 tothe orifice 44 via the control system 30, the drive unit 24, and anelbow connection 48. A pair of nozzles 50 and 52 are associated with theorifices 42 and 44, and are adapted to receive the steam from the tube26 and the water from the tube 46, respectively, and distribute itoutwardly.

In operation, the control system 30 is programmed to periodicallyactuate the drive unit 24, which moves along the tracks 28 and causesthe lance tube 26 and the nozzle 22 to move from their retractedposition to their extended position within the furnace section 10. Thenozzle 22'is continuously rotated, and distributes steam and wateroutwardly through the nozzles 50 and 52, respectively, against the innersurfaces of the walls 12 and 14.

It is understood that since several of these nozzles and associatedstructure will be associated with each wall, the control system 30 isadapted to sequentially actuate the nozzles according to a predeterminedprogram based on the buildup of slag on the walls.

Several variations can be made to the above without departing from thescope of the present invention. For example, the type of fluidsdispensed from the nozzle is not limited to steam and water, but may bein the form of other fluids, such as air or gas, etc. Also, each nozzlecan be provided with more than one orifice for discharging itsrespective fluid. Of course, still other variations of the specificconstruction and arrangement of the apparatus disclosed above can bemade by those skilled in the art without departing from the invention asdefined in the appended claims.

What is claimed is:

1. A slag deposit removal apparatus for cleaning the heat absorptionsurfaces of a vapor generator, said apparatus comprising a plurality ofblast nozzles, each comprising a body portion, at least two fluiddischarge members extending through a wall of said body portion andperpendicular to the longitudinal axes of said body portion; at leasttwo fluid supply means for delivering separate fluids to said dischargemembers, respectively; first drive means for translating said dischargemembers between an operative position inside said furnace and aninoperative position outside said furnace; second drive means forrotating said discharge members in 2. The apparatus of claim 1 whereinsaid discharge members are in the form of nozzles.

3. The apparatus of claim 1 wherein said predetermined sequence is basedon the buildup of slag on said surface.

4. The apparatus of claim 1 wherein said discharge members are axiallyspaced along said body member III I I I i

1. A slag deposit removal apparatus for cleaning the heat absorptionsurfaces of a vapor generator, said apparatus comprising a plurality ofblast nozzles, each comprising a body portion, at least two fluiddischarge members extending through a wall of said body portion andperpendicular to the longitudinal axes of said body portion; at leasttwo fluid supply means for delivering separate fluids to said dischargemembers, respectively; first drive means for translating said dischargemembers between an operative position inside said furnace and aninoperative position outside said furnace; second drive means forrotating said discharge members in their operative positions; andcontrol means for controlling the operation of said discharge members,said fluid supply means and said first and second drive means accordingto a predetermined sequence so that said fluid is discharged against atleast one of said surfaces in a manner to create a combined thermalshock and mechanical force against said surface to cause the separationof slag deposit therefrom.
 2. The apparatus of claim 1 wherein saiddischarge members are in the form of nozzles.
 3. The apparatus of claim1 wherein said predetermined sequence is based on the buildup of slag onsaid surface.
 4. The apparatus of claim 1 wherein said discharge membersare axially spaced along said body member.